Risk assessment tools for use during fabrication of offshore structures and in marine operations projects

摘要

The trend towards most offshore field developments occurring in deep waters has increased the dependency on marine operations in the offshore industry. The installation of subsea templates as well as offshore floating units all year around is profitable from a net present value point of view, but the risk involved to the owners is increasing when working off the good weather season. This calls for analysis of the risk and identification of efficient risk reducing measures. In this paper the effect of setting proper weather criteria for the marine operations and to reduce the uncertainty in the weather forecast is highlighted. During the latest years severe losses have been reported as caused by failures during marine operations. The need for risk analysis of marine operations is therefore underlined. This calls for an overview of the tools available to analyze the risk during marine operations. In this paper some different assessment tools are reviewed and recommendations are given as to the appropriateness of using these tools. Both qualitative and quantitative tools are discussed with a general recommendation of employing the more sophisticated tools when the consequences are large. Qualitative analysis should normally be carried out before any quantitative analysis. For marine operations the experience database is insufficient to pro duce a reliable database of the probability of failures. This calls for expert judgements. The assessors judgements can be seen as their best estimate, including the uncertainty (the Bayesian approach) and will, therefore, be no more reliable than the experience of the experts.